There are a variety of situations in which an internal combustion engine will not function properly without preheating. For example, in extremely cold weather machinery employing engines can become inoperative when the engine is too cold to start.
The need for engine preheating is particularly acute in the fields of auto and boat racing. The clearances between components of an engine are greater when the engine is operated cold than when it is operated at normal operating temperature. The clearances must be sufficient to prevent their chafing against each other during cold starting and when operated at temperatures below operating temperature. Racing engines develop maximum power when the clearances are at their minimum and the engine coolant temperature is in the 190 to 220 degrees Fahrenheit range. Because the metal components of a racing engine expand significantly as the engine heats from its cold state to operating temperature, the clearances between its components significantly widen when the engine cools. Therefore, it is necessary to provide overly large clearances (especially piston-to-cylinder clearances and piston ring end clearance) in cold engines to prevent scuffing or galling of the components during the period before the cold engine reaches normal operating temperature. These overly large clearances negatively impact racing performance.
Excessive clearances between components existing while the engine is cold can also cause leakage damage when the engine is operated while cold. For example, if the clearances between a piston and cylinder in a cold engine are too large, oil can pass between them and contaminate the combustion chamber and piston top. This forms carbon deposits which can cause power robbing detonation and compression gas blow-by during engine operation.
Further, because the engine's components expand unequally as the engine is heated naturally by its own combustion, the engine may sustain damage when started cold. The engine's combustion does not transfer heat equally to each engine component. As a result, some engine components undergo more thermal expansion than others because more heat is applied to them. These problems may be exacerbated by differences in the thermal rates of expansion of the engine components, which typically are made of different materials. Because the engine components expand at different rates, they may abrade or break each other where they are forced into undesired contact. For example, when an engine is running, its combustion heat (usually about 1,500 degrees Fahrenheit) is applied directly to the top of each piston and the top piston ring. If the piston top expands more quickly than does the cylinder in which the piston is housed, the piston will scuff against the cylinder. If the piston ring expands faster than the cylinder, the ring end gap will close, resulting in a broken ring or broken piston ring land.
The need for engine preheating is particularly acute in alcohol-fueled racing engines. The cooling effect of the alcohol fuel drawn into the engine during operation prevents the engine from gaining heat as quickly as would a gasoline-powered engine. This increases the time during which the engine operates at less than full operating temperature which aggravates the problems described above.
Components used in race engines are subjected to extremely high pressures due to high spring pressures and high combustion pressures, making proper lubrication of the components essential. By preheating the engine to heat the oil in the oil pan as well as the engine components, the warm oil will flow more easily through oil passages in the engine to the warm metal surfaces of the components and will have better adhesion to the warmed surfaces of the components. This provides increased lubrication ability.
Consequently, racing engines should be brought as close as possible to operating temperature prior to being operated at high rpm and full power. While many engine heaters have been developed, many are unfeasible for use with racing engines. Engine heaters which are permanently mounted on the engine add undesirable weight to the vehicle and incorporate equipment into the vehicle which can hamper the efficiency of the vehicle's cooling system or cause breakdown of the cooling system if the equipment fails. Non-portable engine heaters typically cannot be brought to a racing site. Portable butane-fired heaters or the like which blow hot air onto the exterior of an engine do not evenly heat the engine's coolant and other internal and external components. Further, those heaters which use a water tube type heat exchanger to transfer heat from hot gasses produced from burning butane to the coolant do not adequately control temperature, and cause coolant in the tubes to boil as the result of applying high temperature gases to the outer surface of the metal tubes, thereby introducing air into the coolant system. Air in the coolant system prevents the coolant from carrying off heat, decreasing engine power and potentially causing catastrophic engine failure. These heaters are also generally unadvisable and often prohibited for use in racing areas because they produce an open flame as their method of heating.
Accordingly, it is a primary object of the present invention to provide a heating and pressurization system for liquid-cooled internal combustion engines which can produce or sustain operating temperature in the engine by evenly heating the engine's components through circulation of heated coolant through the engine's coolant system and doing this in a reasonable amount of time.
Another object of the present invention is to provide a portable heating and pressurization system which can be used to produce or sustain operating temperature in a racing vehicle's engine between individual races at a race site.
A further object of the present invention is to use liquid pressure from the pump to pressurize the cooling system of an engine being preheated to increase the boiling point of the coolant in the cooling system.
Yet another object of the present invention is to provide a portable heating and pressurization system for a liquid-cooled internal combustion engine which can be easily connected to and disconnected from the engine without introducing air into the engine's coolant system.
A still further object of the present invention is to provide a heating and pressurization system which can be applied to an internal combustion engine during its machining operations so that the clearances between its components can be measured and machined precisely for minimum clearances to provide optimal functioning at operating temperature.
Other objects and advantages of the present invention will become apparent when the heating and pressurization system of the present invention is considered in conjunction with the accompanying drawings, specification, and claims.